Rotary magazine for bolt action rifle

ABSTRACT

A spring driven rotary magazine for a bolt action rifle, which is actuated responsive to operation of the bolt. A lever system is employed for coupling the bolt and the magazine, and can be manually operated to remove the cartridges without operation of the bolt when the bolt is withdrawn. A cartridge tip protector is employed within the magazine to prevent jamming of the cartridges.

United States Patent I I I 1 3,745,687

Koon, Jr. 1 July 17, 1973 ROTARY MAGAZINE FOR BOLT ACTION 696,l l8 3/1902 'lhorsen 42 19 RIFLE 715,773 l2/l902 Farwellm, 42/19 1,696,537 l2/l928 Kewish 42 19 [75] Inventor: Homer E. Koon, Jr., Denton, Tex.

(731 Assignee: Firearm Development, Inc., Denton,

Tex.

[22] Filed: Apr. 7, 1971 [2]] Appl. No.: 132,145

[52] US. Cl. 42/19 [51] Int. Cl F411: 13/00, F4lc 25/10 [58] Field of Search 42/19 [56] References Cited UNITED STATES PATENTS 483,229 9/1892 Lindner 42/l9 608,023 7/1898 42/]9 Primary Examiner-Benjamin A. Borchelt Assistant ExaminerC. T. Jordan AltomeyTh0mas A. Harwood [57] ABSTRACT A spring driven rotary magazine for a bolt action rifle, which is actuated responsive to operation of the bolt. A lever system is employed for coupling the bolt and the magazine, and can be manually operated to remove the cartridges without operation of the bolt when the bolt is withdrawn. A cartridge tip protector is employed within the magazine to prevent jamming of the cartridges.

10 Claims, 9 Drawing Figures PATENIH] JUL 1 7 I973 SIEU 2 If 3 INVENTUR HOMER E. KOON,JR.

ATTORNEY PATENTED JUL 1 1 ms SHEET 3 [1F 3 INVEN TOR I In I" HOMER E. KOON, JR.

ATTORNEY ROTARY MAGAZINE FOR BOLT ACTION RIFLE This invention relates to a bolt action rifle and more particularly to a rotary magazine for a bolt action rifle.

For several reasons, rotary magazines are not used as extensively in rifles as are the staggered box type magazines. For example, in order to empty a rotary magazine used with a bolt action rifle, the bolt must be operated or withdrawn each time a cartridge is removed, until the magazine is completely empty. This is in contrast to the opening of a floor plate on a staggered box magazine to empty all cartridges in one operation. As another example, rotary magazine constructions are usually complex and more expensive to manufacture than the staggered box type magazine, whereas the latter is very simple in construction and usually comprises only a box having a spring loaded lifter.

Although staggered box type magazines are by far the most commonly used, there are also certain disadvantages of this type when used in conjunction with a bolt action rifle. One major disadvantage is the relatively poor feeding ability of the system. That is to say, the bolt is employed to remove a cartridge from the magazine in order to chamber the cartridge. The front face of the bolt picks up the butt of the cartridge as the bolt is moved forwardly, thereby urging the cartridge forward over a ramp and into the chamber. However, only a small percentage of the area of the butt of the cartridge is engaged by the face of the bolt as the cartridge is initially picked up, thus causing the cartridge to be moved over a very substantial angle, into the chamber. This often causes rough operation of the bolt action, and in some instances with larger calibers, jamming often occurs.

Because of the general construction of rotary magazines, the feeding of the cartridges into the chamber from the magazine is much less of a problem. This is because the magazine, when actuated, rotates a cartridge up into the receiver in front of the bolt, whereby a very large percentage of the area of the butt of the cartridge is initially placed in front of the face of the bolt. Thus the cartridge, when chambered, is moved over a very gentle ramp, or small angle. Consequently, much smoother operation is achieved and the possibility of jamming is minimized.

The present invention provides a rotary magazine for use in conjunction with a bolt action rifle, wherein the feeding advantage of a rotary magazine is achieved while eliminating many of the other disadvantages normally associated with the construction and operation of rotary magazines. Briefly, the rotary magazine of the invention is spring driven and is actuated for feeding cartridges responsive to operation of the bolt. Normal operation of the bolt causes the magazine to feed a cartridge into the receiver when the bolt is withdrawn, so that the cartridge can be chambered by the bolt when the bolt is closed and locked. At the same time, the magazine is actuated to present another cartridge into the receiver in front of the bolt on the next operation of the bolt. A lever system is employed to provide the functional coupling between the bolt and the rotary magazine, which lever system also can be manually operated when the bolt is withdrawn to quickly remove all cartridges from the magazine without the successive operation of the bolt for each cartridge contained therein. This same lever system acts as a stop to limit the rearward movement of the bolt so as to prevent the bolt being completely removed from the receiver upon normal operation, but which also selectively permits the complete removal of the bolt from the receiver. A tip protector is provided in the rotary magazine to prevent jamming of the cartridges, and to maintain them in proper position.

Many other objects, features and advantages of this invention will become readily apparent from the following detailed description thereof when taken in con junction with the appended claims and the attached drawing wherein like reference numerals refer to like parts throughout the several figures, and which:

FIG. 1 is a side elevational view, in section, of the rotary magazine of the invention showing, in fragmentary view, the bolt and receiver of the bolt action rifle, with the bolt in the locked position;

FIG. 2 is a front elevational view, in section, of the action and magazine of FIG. 1, taken through section lines 2-2 of FIG. 1;

FIG. 3 is a fragmentary, perspective view of the bolt employed with the action of FIG. I;

FIG. 4 is an end elevational view, in section, of the rotary magazine taken through section lines 44 of FIG. 1;

FIG. 5 is a fragmentary top view, partly in section, taken through section lines 5-5 of FIG. 1;

FIG. 6 is a side elevational view, in section, of the rotary magazine and bolt action depicted in FIG. I, with the bolt in the forward but unlocked position;

FIG. 7 is a side elevational view, in section, of the rotary magazine and bolt action shown in FIG. I, with the bolt withdrawn to the position where another cartridge can be fed into the receiver in front of the bolt face;

FIG. 8 is a front elevational view, in section, taken through section lines 8-8 of FIG. 7; and

FIG. 9 is the same front elevational view as FIG. 8, but wherein the last cartridge contained within the magazine is in position in front of the bolt face.

Referring particularly to FIGS. 1 and 2, the bolt action rifle comprises a receiver I0 (only fragmentarily shown in FIG. I) having opposing side walls 12 between which the rotary magazine of the invention is contained, and a port 13 opening in the top and side thereof through which cartridges are loaded and unloaded. A bottom floor 14 is secured between the opposing side walls of the receiver by means of a screw I5, wherein this screw is secured into a portion of the receiver forward of the port 13. The bottom floor also includes a trigger guard 11 as an integral part thereof.

The rotary magazine comprises a generally cylindrical housing 16, having an edge 17 thereof turned inward along the entire length thereof for functioning as a ramp on which cartridges are fed into the receiver in front of the bolt face. Ends 42 and 44 are provided on the housing and will be described in more detail hereinafter.

The bolt I8 is shown more clearly in the fragmentary, perspective view of FIG. 3, in which a keyway or slot 20 is provided in a surface along the major length thereof, with the keyway or slot terminating adjacent the rear end ofthe bolt in a ramp 22 that is at a right angle to the slot thereof. The depth of the slot or keyway is constant along its length but tapers up in a ramp 22 to the outside diameter of the bolt. A bolt of any suitable cross-sectional configuration can be employed, such as the customary circular cross-sectional bolt. However, this particular bolt is shown to be substantially octagonal with seven flat sides and one curved side, with the keyway being provided in the curved side, all as shown more clearly in FIG. 4. The purpose for using an octagonal bolt is immaterial to this invention, but it will be noted that this particular bolt eliminates a considerable amount of the friction normally encountered in bolt actions because of the relatively small surface area thereof that engages the inside wall of the receiver. In addition, the flat sides 19 provide spaces between the bolt and receiver in which dirt and grit can be collected to prevent binding of the action during operation.

A lever system is employed for coupling the rotary magazine to the bolt, so that the magazine is operated responsive to operation of the bolt. The rotary magazine itself incorporates a spring drive for feeding the cartridges into the receiver channel, when released, and a star wheel that is engaged by the lever system so that operation of the bolt releases the spring drive.

Referring particularly to FIGS. 1 and 5, it will be seen that the lever system comprises a pin or key 24 contained within a port or hole 27 in the trigger housing, wherein the top portion 25 of the key extends into the keyway 20 of the bolt 18. The pin contains a lower portion 32 of reduced diameter that forms a shoulder 26 concentric with the larger diameter portion 24. The port 27 also defines a concentric shoulder within the trigger housing and a spring 28 is contained between shoulders 26 and 30 for urging pin 24 upwardly. As will be described hereinafter, pin 24 comprises a part of the lever system for providing the coupling between the bolt and the rotary magazine, and is coupled to other portions of the lever system for this purpose.

Front and rear walls 42 and 44, respectively, are provided for the magazine housing 16, and a central shaft 46 extends the length of the housing and is joumaled through openings 54 and 50in the front and rear walls, respectively. The rear portion 51 of shaft 46 is rectangular in cross-section to key into a star wheel 82, so that the star wheel and shaft rotate together. The front part 48 of the shaft is of constant diameter and extends through opening 54 in front wall 42 into recess 49 of the receiver, so that the magazine is supported at the front end. A spring 52 is provided about the front part of the shaft and is secured at the front end to wall 42, such as by brazing for example and at the rear end to shaft 46 through hole 56. The magazine is secured inside the receiver in any suitable manner. Here, rear wall 44 includes tabs "9 and 119 on either side that extend rearward and attach to supports 12] and 121' within the receiver for supporting the magazine at the rear. With the housing of the magazine maintained stationary within the receiver, the shaft 46 is caused to rotate by spring 52 if the spring is wound, provided that the shaft is released and is not otherwise constrained against rotation. Another spring 58, preferably of the watch or leaf type, is provided behind the rear wall 44 of the magazine and is secured at its inner end to the magazine box rear wall 44 through hole and at its outer end to outside housing 80 through hole 62. When the shaft 46 is rotated to wind spring 52, spring 58 is likewise wound. Thus the two springs act together to rotate the shaft of the rotary magazine and provide an even drive on each end thereof.

Cartridges 68 are contained in the rotary magazine about shaft 46, and are loaded therein through port 13 of the receiver when the bolt is in its withdrawn position. The cartridges are of the usual construction and comprise the shell case, also designated numeral 68, with a tapered front end 69, and a slug 70 that projects from the tapered front end. The cartridge also includes a cap 71 constituting the butt thereof.

To maintain the cartridges in the proper position in the rotary magazine and to prevent them from being lodged in a forward position therein, a tip protector or spacer 72 is secured about the shaft 46 intermediate the ends thereof. This protector is generally cylindrical, and includes a rearwardly facing beveled shoulder 73. A lock screw 74 is provided in the tip protector for securing the tip protector to the shaft, and to permit adjustment of the spacer to any position along the length of the constant diameter front portion of the shaft. Shoulder 73 generally conforms to the tapered portion 69 of the cartridge case. Cartridges of different lengths may be accommodated within the rotary magazine by adjusting the location of the tip protector, wherein it is desirable to locate the tip protector so that the cartridges are maintained in a substantially full rearward position.

A curved cartridge follower or feeder 76 comprising an elongated baffle is secured along a portion of the length of the shaft at the rear thereof. With the cartridges loaded as shown in FIGS. I and 2, the feeder 76 bears against the last cartridge (first loaded) to urge cartridges out of the magazine in front of the bolt face when the shaft 46 is caused to be rotated by the springs. The cartridges are forced out of the open top of the magazine housing 16 as shown more clearly in FIG. 2.

Referring to all of FIGS. 1, 4 and 5, the magazine includes a cylindrical enclosure 80 secured to star wheel 82 for rotation therewith, and covers leaf spring 58. The star wheel comprises a plurality of points or projections 84 for being engaged by a pawl, in which the number of points depends upon the cartridge capacity of the magazine. Springs 52 and 58 are wound as the magazine is loaded with cartridges, and it will be seen that these springs will force all cartridges from the magazine in one motion provided port 13 of the receiver is not obstructed by the bolt, and provided further that star wheel 82 is not constrained against rotation.

FIG. 1 shows the bolt in the closed and locked position, so that pin 24 has been caused to ride up on ramp 22 of the keyway and rest on one of the flat surfaces 19 of the bolt. Thus in locking the bolt, pin 24 is depressed into port 27 to release the rotary magazine as will be explained.

The lever system also comprises an arm that is secured between the walls of the trigger housing by means of a pin 92, for rotation in a vertical plane. The arm includes a forward portion 94 that has a forwardly projecting end or pawl 96 depending therefrom for engaging the star wheel 82. As seen in the top view of FIG. 5, the forward portion 94 is laterally offset from the rearward portion, and forms a slot 99, with an arm 98 for accommodating the bottom of pin 24. Pin 24 includes a neck portion 33 of generally rectangular crosssection that fits within slot 99, and a shoulder 34 be' neath the neck that limits the upward movement of the pin as it bears upward against the bottom edge of the slot. Pin 24 is coupled to arm 90 through slot 99 in front of pin 92, so that spring 28 urging pin 24 upward tends to rotate arm 90 in a counterclockwise direction as seen in FIG. I. A support 100 is threaded at 104 into the trigger housing and includes a slot 102 extending horizontally therethrough and opening in the bottom thereof, so that member 94 and pawl 96 are accommodated within the slot. Member 100 acts as a lateral support for the arm 90 to prevent the star wheel from exerting a lateral stress on the arm to cause the lever system to bind and decrease the efficiency of operation of the magazine.

As the bolt is closed and locked, pin 24 rides up on ramp 22 and is depressed, thereby urging arm 90 in a clockwise direction and disengaging pawl 96 from the star wheel 82. Upon disengagement, shaft 46 and feeder 76 are rotated by springs 52 and 58 until the next cartridge to be chambered is fed upwardly against the surface of the bolt, as shown in FIG. 2. However, the amount of rotation is very small since this cartridge is already held just below the bolt, but is sufficient for the point on the star wheel to completely clear pawl 96 when pin 24 is again released to move upward. Thus when the bolt is thereafter unlocked, and withdrawn so that it no longer obstructs the upward movement of this cartridge, the cartridge is fed into the receiver in front of the bolt face.

FIG. 6 is a side elevational view, in section, of the bolt action and rotary magazine shown in FIG. 1, with the bolt forward but rotated to the unlocked position so that it may be withdrawn rearwardly in the receiver. When the bolt is rotated to unlock it, pin 24 is caused to ride down on ramp 22 into keyway 20, thereby allowing the pin to move upwardly through the action of spring 28. This raises arm 90, or causes it to be rotated in a counterclockwise direction, and thus brings pawl 96 upwardly so that it can engage the next point on the star wheel 82. Since the star wheel was previously rotated partially when the bolt was rotated to lock it in place, the pawl 96 is disposed between adjacent points and does not engage the star wheel until the latter has rotated sufiiciently for the next point to engage the pawl.

When the bolt is withdrawn to eject the spent cartridge out port 13, springs 52 and 58 cause the further rotation of shaft 46 and feeder 76 of the rotary magazine, thereby urging the next cartridge upward in front of the bolt face. The bolt rides along on this cartridge as it is withdrawn as seen in FIG. 2. Feeder arm 76 can only rotate until the next point 84 engages pawl 96, whereupon further rotation is precluded. Thus the next cartridge to be chambered is placed in front of the bolt face as shown in the side elevational view, of FIG. 7, and the front elevational view, in section, of FIG. 8. It will be seen that a very large percentage of the area of the butt or cap 71 of the cartridge is placed in front of the bolt face when the bolt is withdrawn. This cartridge is then chambered when the bolt is again slid forward. When the bolt is slid forward and rotated to the locked position, pin 24 is again urged downward to rotate arm 90 in a clockwise direction, so that pawl 96 again disengages the star wheel.

Pin 24 rides in the keyway when the bolt is withdrawn, so that the front wall of the keyway eventually comes to bear against the pin as the bolt is withdrawn to the position shown in FIG. 7. Thus pin 24 acts as a stop to limit the rearward position of the bolt relative to the receiver, and to prevent the bolt from being completely withdrawn from the receiver during normal operation. As will be seen below, however, pin 24 can be actuated so that the bolt can be completely removed from the receiver.

Another arm 110 is connected to arm 90 on the other side of pin 92 through a slot Ill and a pin 112, so that as this arm is moved up and down, arm 90 is caused to be rotated in a clockwise and counterclockwise direction, respectively, as viewed in FIG. I. Slot I ll permits the effective lengthening of arm 90 when pin 110 is pushed upward. The bottom face 116 of the arm can be scored to provide traction for manual operation with the finger. Arm 110 is used for the purpose of unloading the magazine and for actuating the lever system so that the bolt can be completely removed from the receiver. Referring again to FIG. 7 showing the bolt in its rearward position as limited by pin 24 engaging the front wall of keyway 20, the pin 24 can be moved out of engagement from the keyway by urging arm 110 upwardly to rotate arm 90 in a clockwise direction. When pin 24 is caused to clear the outside diameter of the bolt, the bolt can then be completely withdrawn from the receiver. At the same time, pawl 96 is caused to be disengaged from the star wheel 82, so that springs 52 and 58 are free to cause feeder 76 to rotate. Since the bolt no longer obstructs port 13, and since pawl 96 is disengaged from the star wheel, feeder arm 76 is caused to rotate until all cartridges are rotated or rolled out of the magazine through port 13. Thus a quick unloading feature is provided by the rotary magazine without the necessity of successive operations of the bolt to remove individual cartridges.

It is desirable to provide a stop or limit on the rotation of the feeder 76 when the last cartridge is fed upward in front of the bolt face. Referring to the front elevational view, in section, of FIG. 9, wherein the last cartridge (first loaded) is disposed in front of the bolt face, the feeder 76 is in a vertical position and is prevented from further rotation. Further rotation would permit the cartridge to drop back down into the magazine behind the feeder, thus preventing the chambering of this cartridge and the removal from the magazine. To limit the rotational movement of the feeder, a horizontal pin [20 is secured in the rear wall 44 of the magazine and extends rearward thereof, and another but vertical pin 122 is secured in the edge of cylindrical housing 80. Pin 122 is secured in housing at a location so that it engages pin when the feeder 76 attains a substantially vertical position as shown in FIG. 9, thus limiting the rotational movement of the feeder.

Although the invention has been described with reference to a preferred embodiment thereof, certain modifications and substitutions that do not depart from the true scope thereof will undoubtedly occur to those skilled in the art. Therefore, it is intended that the invention be limited only as defined in the appended claims.

What is claimed is:

1. In a bolt action rifle including a receiver having a bolt channel therein, a bolt rotatably and slidably carried in said bolt channel and adapted to be locked against sliding movement in said receiver when rotated to a closed position, a rotary magazine carried by said receiver below said bolt channel for feeding cartridges upward therein, said rotary magazine having a rotating cartridge feeder for feeding cartridges into said bolt channel and spring means for actuating said cartridge feeder, the improvement comprising:

a. first means coupled to said cartridge feeder for rotation therewith,

b. second means for engaging said first means for controlling rotational movement of said cartridge feeder, coupled to said bolt to assume a first position for disengaging said first means when said bolt is rotated from a first position to a second position, and to assume a second position to engage said first means when said bolt is rotated from said second position to said first position to limit said cartridge feeder to a predetermined angle of rotation between said second and said first rotational positions of said bolt.

2. In a bolt action rifle as set forth in claim I wherein said first means comprises a gear, and said second means comprises a pawl for engaging the teeth of said gear.

3. [n a bolt action rifle as set forth in claim 1 wherein said second means includes a pin extending into said bolt channel for engaging said bolt, and said bolt includes means coupled to said pin to move said pin from a first position to a second position when said bolt is rotated from said first position to said second position.

4. In a bolt action rifle as set forth in claim I wherein said second means comprises a member extending into said bolt channel for engaging said bolt, and said bolt includes a slot extending along a part of the length thereof in which said member rides and having a ramp at one end thereof that causes said member to be moved from a first position to a second position when said bolt is rotated from said first position to said second position.

5. In a bolt action rifle as set forth in claim 1 including third means coupled to said second means for manually causing said second means to assume said first position of disengagement of said first means independent of the position of said bolt.

6. In a bolt action rifle as set forth in claim 1 in which said bolt includes a slot extending a part of the length in the surface thereof, and said second means includes a member extending into said bolt channel and said slot in said bolt to limit the rearward position of said bolt relative to said receiver, including third means coupled to said second means to manually withdraw said member from said slot to pennit the complete removal of said bolt from said receiver.

7. In a bolt action rifle as set forth in claim 4 including resilient means biasing said member from said second position to said first position.

8. In a bolt action rifle as set forth in claim I including third means for limiting the rotational position of said cartridge feeder when the last cartridge contained within said magazine is fed upward into said bolt channel.

9. [n a bolt action rifle as set forth in claim I wherein said first means comprises gear means, said second means comprises a lever means supported for rotation in a first plane to positions of engagement and disengagement with said gear means, first arm means coupled between said bolt and said lever means for causing said lever means to be rotated to a position of disengagement with said gear means when said bolt is rotated from an unlocked to a locked position, and for causing said lever means to be rotated to a position of engagement with said gear means when said bolt is rotated from a locked to an unlocked position, and second arm means coupled to said lever means for manual actuation to cause said lever means to be rotated to a position of disengagement with said gear means.

10. In a bolt action rifle as set forth in claim 9 wherein said bolt includes a slot extending along a part of the length thereof in which said first arm means rides and having a ramp at one end thereof that causes said first arm means to be moved in one direction when said bolt is rotated from said unlocked position to said locked position, resilient means biasing said first arm means in an opposite direction, and means relieving said lever means from substantially all stresses other than those exerted thereon in said first plane.

* i t t i 

1. In a bolt action rifle including a receiver having a bolt channel therein, a bolt rotatably and slidably carried in said bolt channel and adapted to be locked against sliding movement in said receiver when rotated to a closed position, a rotary magazine carried by said receiver below said bolt channel for feeding cartridges upward therein, said rotary magazine having a rotating cartridge feeder for feeding cartridges into said bolt channel and spring means for actuating said cartridge feeder, the improvement comprising: a. first means coupled to said cartridge feeder for rotation therewith, b. second means for engaging said first means for controlling rotational movement of said cartridge feeder, coupled to said bolt to assume a first position for disengaging said first means when said bolt is rotated from a first position to a second position, and to assume a second position to engage said first means when said bolt is rotated from said second position to said first position to limit said cartridge feeder to a predetermined angle of rotation between said second and said first rotational positions of said bolt.
 2. In a bolt action rifle as set forth in claim 1 wherein said first means comprises a gear, and said second means comprises a pawl for engaging the teeth of said gear.
 3. In a bolt action rifle as set forth in claim 1 wherein said second means includes a pin extending into said bolt channel for engaging said bolt, and said bolt includes means coupled to said pin to move said pin from a first position to a second position when said bolt is rotated from said first position to said second position.
 4. In a bolt action rifle as set forth in claim 1 wherein said second means comprises a member extending into said bolt channel for engaging said bolt, and said bolt includes a slot extending along a part of the length thereof in which said member rides and having a ramp at one end thereof that causes said member to be moved from a first position to a second position when said bolt is rotated from said first position to said second position.
 5. In a bolt action rifle as set forth in claim 1 including third means coupled to said second means for manually causing said second means to assume said first position of disengagement of said first means independent of the position of said bolt.
 6. In a bolt action rifle as set forth in claim 1 in which said bolt includes a slot extending a part of the length in the surface thereof, and said second means includes a member extending into said bolt channel and said slot in said bolt to limit the rearward position of said bolt relative to said receiver, includinG third means coupled to said second means to manually withdraw said member from said slot to permit the complete removal of said bolt from said receiver.
 7. In a bolt action rifle as set forth in claim 4 including resilient means biasing said member from said second position to said first position.
 8. In a bolt action rifle as set forth in claim 1 including third means for limiting the rotational position of said cartridge feeder when the last cartridge contained within said magazine is fed upward into said bolt channel.
 9. In a bolt action rifle as set forth in claim 1 wherein said first means comprises gear means, said second means comprises a lever means supported for rotation in a first plane to positions of engagement and disengagement with said gear means, first arm means coupled between said bolt and said lever means for causing said lever means to be rotated to a position of disengagement with said gear means when said bolt is rotated from an unlocked to a locked position, and for causing said lever means to be rotated to a position of engagement with said gear means when said bolt is rotated from a locked to an unlocked position, and second arm means coupled to said lever means for manual actuation to cause said lever means to be rotated to a position of disengagement with said gear means.
 10. In a bolt action rifle as set forth in claim 9 wherein said bolt includes a slot extending along a part of the length thereof in which said first arm means rides and having a ramp at one end thereof that causes said first arm means to be moved in one direction when said bolt is rotated from said unlocked position to said locked position, resilient means biasing said first arm means in an opposite direction, and means relieving said lever means from substantially all stresses other than those exerted thereon in said first plane. 